CVE-2026-22809 identifies a Regular Expression Denial of Service (ReDoS) vulnerability in the tarteaucitron.js library, specifically in versions prior to 1.29.0. The vulnerability is categorized under CWE-1333, which pertains to inefficient regular expression complexity. The issue occurs in the processing of the issuu_id parameter, where a crafted input can cause the regular expression engine to consume excessive CPU resources, leading to a denial of service condition. This vulnerability affects the availability of applications that incorporate tarteaucitron.js for cookie banner compliance and accessibility. The CVSS v3.1 score is 4.4 (medium), with the vector indicating that exploitation requires local access (AV:L), low attack complexity (AC:L), high privileges (PR:H), no user interaction (UI:N), and impacts only availability (A:H) without affecting confidentiality or integrity. The vulnerability was publicly disclosed on January 13, 2026, and fixed in version 1.29.0 of tarteaucitron.js. No public exploits have been reported to date. The vulnerability's exploitation could lead to service degradation or downtime in web applications relying on the affected library, particularly in environments where the issuu_id parameter is user-controllable or processed frequently. Given the nature of the vulnerability, it is primarily a denial of service threat rather than data breach or code execution risk.

For European organizations, the primary impact of CVE-2026-22809 is on the availability of web services that utilize vulnerable versions of tarteaucitron.js for cookie consent management. Since cookie banners are mandatory under the EU's GDPR and ePrivacy Directive, many websites in Europe deploy tarteaucitron.js or similar tools. An attacker with local access and high privileges could exploit this vulnerability to cause CPU exhaustion, resulting in service slowdowns or outages. This can disrupt user experience, potentially leading to non-compliance with cookie consent regulations if the banner fails to function properly. Additionally, service unavailability can affect business operations, customer trust, and regulatory standing. Although exploitation requires high privileges and local access, insider threats or compromised accounts could leverage this vulnerability. The lack of impact on confidentiality and integrity limits the risk to data breaches, but availability issues remain a concern, especially for high-traffic websites and services critical to customer interaction and regulatory compliance.

European organizations should immediately upgrade tarteaucitron.js to version 1.29.0 or later, where the vulnerability is fixed. In environments where upgrading is not immediately feasible, organizations should implement input validation and sanitization on the issuu_id parameter to prevent malicious regular expression inputs. Monitoring CPU usage and application performance metrics can help detect potential exploitation attempts early. Restricting local access and enforcing strict privilege management reduces the risk of exploitation, given the requirement for high privileges. Additionally, organizations should conduct regular dependency audits to identify vulnerable library versions and apply patches promptly. Web application firewalls (WAFs) can be configured to detect and block suspicious patterns targeting the issuu_id parameter. Finally, educating developers and system administrators about ReDoS risks and secure coding practices related to regular expressions can prevent similar vulnerabilities.